Shulte chose several areas in the lower chesapeake bay as his experimental sites. at each site, he constructed artificial reefs of two different heights. he also left portions of each site unrestored to serve as points of comparison. oysters were allowed to colonize the reefs and the unrestored bay bottom safe from harvesting. his hypothesis was that oysters would survive better in the plankton-rich upper waters away from the smothering sediments and hypoxic waters of the bay bottom. a) reef type is the independent variable. b) adult oyster density is a dependent variable. c) spat density is a dependent variable. d) high-relief and low-relief reefs are treatments.

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.

Several billion years ago which gas was the least prevailant in the atmosphere

In order to study genetic mutations, scientists must study genetic material. which statement describes the genetic material scientists are most likely studying? a) they study alleles that contain chromosomes, which are rna.b) they study alleles that contain genes, which are chromosomes.c) they study chromosomes that contain genes, which are dna segments.